herring_csv2gpiper: Read in a herring baseline file and make a gPiper data frame...
In eriqande/herring: genetic stock identification of river herring

Read in a herring baseline file and make a gPiper data frame out of it

1	herring_csv2gpiper(baseline_path, lat_long_path, locus_columns)

`baseline_path`	Path to a baseline file that is in the (csv) format that Dan H uses. See alewife-baseline.csv for an example. Importantly, the file must have a column called Drainage.code that has the drainage codes as in DH's file.
`lat_long_path`	Path to a text file with lats and longs of the pops in the baseline file. See file alewife-lat-long.txt for an example.
`locus_columns`	integer vector with the columns in the original CSV file that have the loci that you want to use. Should be twice as many columns as loci. In alewife-baseline.csv this is